Adriaan Daniël Fokker was a prominent Dutch theoretical physicist. He is known in theoretical physics for the Fokker-Planck equation and his work on the theory of relativity. In the years around 1930, however, Fokker also became interested in room acoustics and the tuning of musical instruments. He designed several sound reflectors, which amplify the sound reaching the audience, especially in churches, but his work on musical instrument tuning is what made him more widely known.
Cornelis Zwikker was a Dutch physicist and one of the initiators of the Dutch Sound Foundation. After studying chemistry, mathematics, and physics in Amsterdam, he worked with Philips in Eindhoven until 1929, when he was appointed professor of theoretical and applied physics at the Delft University of Technology. Zwikker was responsible for the acoustic design of many buildings, among them the studios of the Dutch broadcasting organization AVRO.